Germ cells are set aside from other lineages early in development, and differentiate into functioning gametes. To understand germ cell differentiation would be a major achievement in biology, and would provide important insights into infertility, contraception, human congenital diseases, germ line tumors, as well as the preservation of endangered species. The molecular basis of germ cell differentiation is beginning to be understood, due to major intellectual and technical advances. General mechanisms that unite both vertebrates and invertebrates are beginning to emerge. This meeting will provide a public forum for discussion of all aspects of germ cell research, from the primordial germ cell to the functioning gamete, in diverse model organisms. We expect to attract 200-250 participants from all over the world. There are no competing meetings that are so wide in scope. Six topics have been chosen for platform presentations: The early germ line, Regulation of germ cell gene expression, Meiosis, Sperm differentiation, Oogenesis and egg polarity, Fertilization and gamete function. Each will be organized and co-chaired by two experts in the topic, who will invite half the speakers, and select the other half from submitted abstracts. We will encourage platform presentations from young scientists. The meeting will facilitate interactions between scientists who study different model systems, and different aspects of germ cell differentiation.